It is the specific aim of this proposal to develop an advanced adhesive and dental restorative system that is more quickly placed and reliable than current products. Thus improving patient satisfaction and general health care. The method for achieving this objective is to design a dental bonding agent and restorative system that are structurally controlled at the nanoscopic (1-10nm) level through the macroscopic level. Natural tooth contains both nanoscopic and macroscopic length scales. The development of such a restorative system will maintain the continuum of structure from the natural tooth through the adhesive and restorative system thereby improving compatibility and physical properties. Nanoscopic building blocks based on the nontoxic polyhedral oligomeric silsesquioxane (POSS) Nanostructured TM Chemical technology will be utilized in combination with conventional macroscopic and nanoscopic metal oxide fillers to design a dental restorative which benefits from multi-length scale structural control (nano to macro). POSS-Monomers will be utilized as isotropic 1.5nm structural segments in the base restorative resin. In this capacity the resulting nanostructured resin will provide an enhanced filler-resin interaction and lower shrink characterists as demonstrated in Phase I. Improvement of the filler-resin interface will also result in improved mechanical properties and reduced degradation of the restorative system. The performance of restoratives are also governed by the nature and integrity of the inherent bondline formed with natural tooth. Here again the design of bonding agents which utilize 1.5nm monomeric POSS building blocks provide a more natural interface with the 2nm sized apatite crystals present in natural tooth and with the l nm-10nm structural segments incorporated into the proposed restorative. Overall better bonding to the tooth and restorative per Phase I findings. By utilizing both nano (lnm-10nm) and macroscopic length scales in a dental restorative and bonding system, a continuation of length scale and properties with those in natural tooth can be acheived. It is the intent of the proposed Phase II work to develop a prototype system for transition to Phase III.